1. Field of the Invention
The present invention relates to scroll machines, and in particular, to scroll compressors.
2. Description of the Related Art
Referring to FIGS. 1-4, a known scroll compressor 10 is shown, which includes main housing 12, bottom cap 14 with base 16 secured to the lower end of housing 12, and a separator plate 18 and top cap 20 each secured to the upper end of housing 12 by a welding, brazing, or other suitable operation to define an enclosed hermetic housing in which the motor-compressor unit 22 of compressor 10 is disposed. Motor-compressor unit 22 generally includes a first, fixed scroll 24, a second, orbiting scroll 26, crankcase 28, drive shaft 30, stator 32, rotor 34, and outboard bearing assembly 36. Separator plate 18 is secured around its perimeter to the interior of housing 12, such as by welding, and divides the interior of the housing 12 into a suction chamber 38 in fluid communication with suction port 40 in housing 12, and discharge chamber 42 in fluid communication with discharge port 44 in top cap 20. Scroll compressor 10 is similar to the scroll compressor discussed in detail in U.S. Patent Application Publication No. US 2004/0047754 A1, application Ser. No. 10/235,214, entitled OIL SHIELD AS PART OF CRANKCASE FOR A SCROLL COMPRESSOR, filed on Sep. 5, 2002, assigned to the assignee of the present invention, the disclosure of which is expressly incorporated herein by reference.
Fixed scroll 24 is secured to separator plate 18, such as by a plurality of bolts 72 disposed radially outwardly of separator plate hole 19, and includes outer wall 46 extending from base plate 48, and an involute wrap 50 extending from base plate 48 and disposed inwardly of outer wall 46. Fixed scroll 24 further includes a plurality of mount flanges 52 spaced radially about the end of outer wall 46 opposite base plate 48, and a plurality of bolts (not shown) secure mount flanges 52 to crankcase 28. Crankcase 28 includes main bearing 54 in which the upper portion of drive shaft 30 is rotatably supported. Stator 32 is fixed within housing 12 and is connected to outboard bearing assembly 36 and crankcase 28 in a suitable manner. Drive shaft 30 is secured to rotor 34 in a suitable manner, and outboard bearing assembly 36 includes outboard bearing 56 which supports a lower end of drive shaft 30. The upper portion of drive shaft 30 includes an eccentric end mounted within annular hub 58 extending downwardly from base plate 60 of orbiting scroll 26. Orbiting scroll 26 additionally includes an involute wrap 62 extending upwardly from base plate 60 thereof, which is in meshing relationship with wrap 50 of fixed scroll 24. Oldham coupling 64 is operatively coupled between orbiting scroll 26 and crankcase 28 to prevent rotation of orbiting scroll 26, as is known.
Additionally, fixed scroll 24 includes discharge outlet 68 in base plate 48. Discharge outlet 68 may be substantially centrally located within fixed scroll 24 and may be aligned with separator plate hole 19 of separator plate 18.
In operation, electrical energization of stator 32 rotatably drives rotor 34 and drive shaft 30 to move orbiting scroll 26 in an orbiting manner with respect to fixed scroll 24. A working fluid at suction pressure is drawn from suction chamber 38 into a suction inlet 66 of fixed scroll 24, and is compressed within the plurality of variable volume, working pockets or compression chambers 55 which are defined between wraps 50 and 62 of fixed and orbiting scrolls 24 and 26, respectively, as orbiting scroll 26 rotates in a known manner. The compressed working fluid is then discharged through discharge outlet 68 in base plate 48 of fixed scroll 24, through discharge check valve assembly 70, and through separator plate hole 19 aligned with discharge outlet 68 into discharge chamber 42 at a discharge pressure. The discharge pressure working fluid exits compressor 10 through discharge port 44 to enter components of a refrigeration system (not shown).
Referring to FIGS. 2-4, gasket 74 ideally prevents potential leakage of discharge pressure working fluid from exiting discharge chamber 42 and returning to suction chamber 38, such as via a path denoted by Arrow C, shown in FIG. 4. However, a minimal gap may exist between separator plate 18 and gasket 74, or alternatively between fixed scroll 24 and gasket 74, which may permit discharge pressure working fluid to escape to suction chamber 38. Discharge pressure working fluid potentially may also leak around bolts 72 in a direction generally denoted by Arrow A and return to suction chamber 38 via the minimal gap denoted by Arrow C between separator plate 18 and gasket 74, or alternatively between fixed scroll 24 and gasket 74. Additionally, discharge pressure working fluid potentially may enter the gap denoted by Arrow C between separator plate 18 and gasket 74, or alternatively between fixed scroll 24 and gasket 74, via a path through separator plate hole 19 denoted by Arrow B. Once discharge pressure working fluid enters the gap denoted by Arrow C, the working fluid may enter suction chamber 38 in the direction generally denoted by Arrow D.
Additionally, internal pressure relief valve (IPRV) 76 is disposed in and threaded into separator plate 18, as shown in FIG. 3. IPRV 76 allows discharge pressure working fluid to be vented from discharge chamber 42 to suction chamber 38 in the event of overpressurization. IPRV 76 is accommodated in a recess formed near the outer periphery of fixed scroll 24. Consequently, gasket 74, which is designed to seal fixed scroll 24 and separator plate 18, is notched to a reduced width to clear IPRV 76. Therefore, the robustness of gasket 74 is undermined in the area around IPRV 76.
The above-described potential leak paths potentially reduce the efficiency of scroll compressor 10, thereby lowering productivity of the refrigeration system as a whole.
What is needed is a scroll compressor which is an improvement over the foregoing.